Removal of gallium and gallium containing materials

ABSTRACT

Methods of removing gallium and gallium-containing materials from surfaces within a substrate processing chamber using a cleaning mixture are described. The cleaning mixture contains an iodine-containing compound and is introduced into the processing chamber. Iodine reacts with gallium resident within the chamber to produce thermally volatile Gal 3 . The Gal 3  is removed using the exhaust system of the chamber by raising the temperature of the desorbing surface. Other volatile gallium-containing by-products may also be formed and removed from the exhaust system.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Prov. Pat. App. No. 61/241,287 filed Sep. 10, 2009, and titled “ETCH AND CLEAN PROCESSES,” which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

Semiconducting materials having direct or nearly direct bandgap are used to efficiently generate and detect optical radiation. A broad class of direct bandgap materials are called III-V semiconductors, which are composed of a group III material combined with a group V material. The size of the direct handgap determines the optical wavelength of emitted light. The direct bandgap size also determines the minimum wavelength of a photon which can be absorbed by a III-V photodetector to form an electron-hole pair.

Gallium is commonly used as a group III element when forming III-V semiconductors. Deposition may involve sequential or concurrent exposure of a substrate to a gallium source (such as tri-ethyl gallium (TEG) or tri-methyl gallium (TMG)) and a group-V precursor (i.e. NH₃ or AsH₃) in a CVD chamber. Chlorine etchants are used to remove residue from interior surfaces of CVD chambers during preventative maintenance procedures. The etch rates of III-V semiconductors and gallium deposits remain low for these established chemistries and recipes.

Thus there is a need for etch processes which can remove gallium-containing materials more rapidly without increasing the frequency of preventative maintenance procedures.

BRIEF SUMMARY OF THE INVENTION

Methods of removing gallium and gallium-containing materials from surfaces within a substrate processing chamber using a cleaning mixture are described. The cleaning mixture contains an iodine-containing compound and is introduced into the processing chamber. Iodine reacts with gallium resident within the chamber to produce thermally volatile Gal₃. The Gal₃ is removed using the exhaust system of the chamber by raising the temperature of the desorbing surface. Chlorine dioxide may be included in the cleaning mixture, in part, to assist in the removal of any carbon-containing contaminants. Other volatile gallium-containing by-products may also be formed and removed from the exhaust system.

Embodiments of the invention include methods of removing gallium-containing contaminants from a processing chamber. The methods may include adjusting the temperature of the chamber above 200° C. and introducing a cleaning gas mixture to the chamber. The cleaning mixture includes at least one iodine-containing compound. The methods may further include reacting the gallium-containing contaminants with the iodine-containing compound to form a volatile gallium-and-iodine containing reaction product. The methods may still further include removing the gallium-and-iodine containing reaction product from the chamber.

Embodiments of the invention also include methods of cleaning a gallium-containing processing chamber. The methods may include adjusting the temperature of the chamber above 200° C. and introducing a cleaning gas mixture to the chamber. The cleaning mixture includes at least one iodine-containing compound. The methods may further include evacuating the chamber after the introduction of the cleaning gas mixture.

Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosed embodiments. The features and advantages of the disclosed embodiments may be realized and attained by means of the instrumentalities, combinations, and methods described in the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosed embodiments may be realized by reference to the remaining portions of the specification and the drawings.

FIG. 1 is a flowchart of a processing chamber cleaning process according to disclosed embodiments.

FIG. 2 is another flowchart of a processing chamber cleaning process according to disclosed embodiments.

In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

DETAILED DESCRIPTION OF THE INVENTION

Methods of removing gallium and gallium-containing materials from surfaces within a substrate processing chamber using a cleaning mixture are described. The cleaning mixture contains an iodine-containing compound and is introduced into the processing chamber. Iodine reacts with gallium resident within the chamber to produce thermally volatile Gal_(a). The Gal_(a) is removed using the exhaust system of the chamber by raising the temperature of the desorbing surface. Other volatile gallium-containing by-products may also be formed and removed from the exhaust system.

In order to better understand and appreciate the invention, reference is now made to FIG. 1 which is a flowchart of a processing chamber (for example, an MOCVD chamber) cleaning process according to disclosed embodiments. The process begins when some or all interior surfaces of a processing chamber are raised above 200° C. (operation 110). A cleaning gas mixture including an iodine-containing compound is introduced to the processing chamber (operation 115) and reacts with a contaminant on an interior surface of the processing chamber (operation 120). Reaction by-products or reacted contaminants are removed from the chamber through the exhaust system (operation 125).

The cleaning gas mixture includes at least one iodine-containing compound, which may be iodomethane (CH₃I), trifluoroiodomethane (CF₃I), iodine pentafluoride (IF₅), iodobromide (IBr), in embodiments of the invention. The iodine bonds with gallium within the contaminant and forms Gal₃ which is thermally desorbed at the elevated temperature of the interior surfaces of the processing chamber. The temperature of the interior surfaces may be raised above 200° C. 300° C. or 345° C. in embodiments of the invention. Performing the cleaning procedure at elevated temperature shifts the equilibrium of the chemical reaction toward the reactants. This equilibrium shift reduces the favorability of traditional cleaning agents (e.g. chlorine) and makes iodine-containing compounds a relatively more appealing choice. Fluorine, chlorine and bromine each of have properties which can degrade non-contaminant features within the substrate processing chamber. Exemplary contaminants include gallium, gallium nitride, gallium arsenide and other gallium-containing residue from a variety of deposition processes for which the processing chamber is used. Removal of the contaminants improves the quality of post-clean deposition, for example, by reducing defect density or restoring electrical or optical properties of deposited films to nearly those achievable with a residue-free chamber.

The reacted contaminants may include Gal; but may also include alkyl-gallium compounds which are easily desorbed from chamber surfaces. Alkyl-gallium compounds may be formed and desorbed when one or both of iodomethane and trifluoroiodomethane is present in the cleaning gas mixture. Any combination of the iodine-containing compounds described (or similar to those described) may be used to form the cleaning gas mixture.

Chlorine dioxide may also be included in the cleaning gas mixture. FIG. 2 is another flowchart of a processing chamber cleaning process according to disclosed embodiments. A cleaning gas mixture containing chlorine dioxide is flowed into the substrate processing chamber (operation 210). Chlorine dioxide is reacted with gallium-containing contaminants to form some reacted contaminant (operation 215). However, oxygen content is still available to react with carbon-containing contaminant resident on interior surfaces of the chamber to form additional reacted contaminant (220). Both reacted contaminants are removed from the chamber through the exhaust system (operation 325). Chlorine dioxide may be included in any of the iodine-containing cleaning mixtures described herein to address carbon-containing contaminants or carbon content within a gallium-containing film on a substrate.

As used herein “substrate” may be a support substrate with or without layers formed thereon. The support substrate may be an insulator or a semiconductor of a variety of doping concentrations and profiles and may, for example, be a semiconductor substrate of the type used in the manufacture of integrated circuits. The term “precursor” is used to refer to any process gas which takes part in a reaction to either remove material from or deposit material onto a surface. A gas (or precursor) may be a combination of two or more gases (or precursors) and may include substances which are normally liquid or solid but temporarily carried along with other “matrix gases” or, synonymously, “carrier gases”. Matrix gases or carrier gases may be an “inert gas” which refers to any gas which does not form chemical bonds when etching or being incorporated into a film. Exemplary inert gases include noble gases but may include other gases so long as no chemical bonds are formed when (typically) trace amounts are trapped in a film. The terms “trench” and “gap” are used throughout with no implication that the etched geometry has a large horizontal aspect ratio. Viewed from above the surface, trenches and gaps may appear circular, oval, polygonal, rectangular, or a variety of other shapes. The term “via” is used to refer to a low aspect ratio trench (as viewed from above) which may or may not be filled with metal to form a vertical electrical connection.

Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosed embodiments. Additionally, a number of well known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are'also included.

As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a process” includes a plurality of such processes and reference to “the dielectric material” includes reference to one or more dielectric materials and equivalents thereof known to those skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and “includes” when used in this specification and in the following claims are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups. 

1. A method of removing gallium-containing contaminants from a processing chamber, the method comprising: adjusting the temperature of the chamber above 200° C.; introducing a cleaning gas mixture to the chamber, wherein the cleaning mixture comprises at least one iodine-containing compound; reacting the gallium-containing contaminants with the iodine-containing compound to form a volatile gallium-and-iodine containing reaction product; and removing the gallium-and-iodine containing reaction product from the chamber.
 2. The method of claim 1, wherein the iodine-containing compound comprises an iodocarbon compound or iodofluorocarbon compound.
 3. The method of claim 2, wherein the iodocarbon comprises CH₃I.
 4. The method of claim 2, wherein the iodofluorocarbon comprises CF₃I.
 5. The method of claim 1, wherein the iodine-containing compound comprises IF₅ or IBr.
 6. The method of claim 1, wherein the temperature is adjusted to about 300° C. or more.
 7. The method of claim 1, wherein the temperature is adjusted to about 345° C. or more.
 8. The method of claim 1, wherein the gallium-and-iodine containing reaction product comprises GaI₃.
 9. The method of claim 1, wherein the processing chamber further comprises carbon-containing contaminants.
 10. A method of cleaning a gallium-containing processing chamber, the method comprising: adjusting the temperature of the chamber above 200° C.; introducing a cleaning gas mixture to the chamber, wherein the cleaning mixture comprises at least one iodine-containing compound; and evacuating the chamber tiller the introduction of the cleaning gas mixture.
 11. The method of claim 10, wherein the iodine-containing compound is selected from the group consisting of CF₃I, CH₃I, IF₅, and IBr.
 12. The method of claim 10, wherein the temperature is adjusted to about 345° C. or more.
 13. The method of claim 10, wherein the method further comprises introducing ClO₂ to the chamber.
 14. The method of claim 13, wherein the cleaning gas mixture comprises ClO₂.
 15. The method of claim 10, wherein the processing chamber part of a system for fabricating light-emitting-diodes. 